Circadian rhythms and glial cells of the central nervous system

Glial cells are the most abundant cells in the central nervous system and play crucial roles in neural development, homeostasis, immunity, and conductivity. Over the past few decades, glial cell activity in mammals has been linked to circadian rhythms, the 24-h chronobiological clocks that regulate many physiological processes. Indeed, glial cells rhythmically express clock genes that cell-autonomously regulate glial function. In addition, recent findings in rodents have revealed that disruption of the glial molecular clock could impact the entire organism. In this review, we discuss the impact of circadian rhythms on the function of the three major glial cell types – astrocytes, microglia, and oligodendrocytes – across different locations within the central nervous system. We also review recent evidence uncovering the impact of glial cells on the body's circadian rhythm. Together, this sheds new light on the involvement of glial clock machinery in various diseases.     

The Natural Occurrence of Chickpea Chlorotic Dwarf Geminivirus in Chickpea and Faba Bean in the Sudan

A survey of faba bean and chickpea for virus infection, conducted during February 1994 in the Sudan, showed that bean yellow mosaic potyvirus and broad bean mottle bromovirus occurred commonly in both crops. Chickpea chlorotic dwarf geminivirus (CCDV) was detected for the first time in naturally infected chickpeas and faba beans. This is the first report of natural CCDV infection of chickpeas outside India and the first record of chickpea and faba bean infection in West Asia and North Africa (WANA).     

Carbohydrates of the brown seaweed Dictyota dichotoma

The fucose-containing polysaccharides of the brown alga Dictyota dichotoma were extracted with either trichloroacetic acid or HCl to give both water-soluble and water-insoluble materials. The latter had a high proportion (16 to 11%) of protein, and although all the sugars found in the water-soluble extracts were present, the major sugar in these water-insoluble polysaccharides was glucose. The water-soluble material extracted with HCl was a protein-free sulphated heteropolysaccharide. Complete removal of a glucan from the water-soluble extract was achieved by fractional precipitation with ethanol. The recovered glucan-free sulphated polysaccharide, which was rich in glucuronic acid, galactose, fucose and sulphate, showed high anticoagulating activity.     

Utilization of kerosene by a hydrocarbon-assimilating strain of Fusarium oxisporum

Fusarium oxysporum IFO 6384 was grown in three different media, one containing glucose and two containing kerosene as carbon source. One of the kerosene media contained also Tween 60. The harvested dry mats were weighed at various stages of growth. Substitution of glucose with kerosene led to a sharp drop in the production of fungal mycelia. Analysis of the mat samples representing maximum yields indicated that the mycelia grown in the kerosene media were richer in free amino acid and poorer in protein as well as in polymeric and low-molecular weight carbohydrates than those grown in the glucose medium. Treatment of the culture filtrates with three volumes of acetone led to the separation of two fractions. In the first, acetone soluble fraction the free sugars and amino acids were determined, whereas the second, acetone precipitable one, was examined for its proteolytic activity. The gelatinase activity of the acetone precipitable material (APM) obtained from the kerosene media was lower than that from the glucose medium. The former activity, in contrast to the latter reached its maximum and minimum values at pHs 4 and 9, respectively.     

In vitro studies on the growth of Shigella sonnei by Lactobacillus casei and Lact. acidophilus.

The inhibitory effect of lactobacilli on growth of Shigella sonnei was studied. The effect was not due to pH alone, as addition of hydrochloric, lactic or acetic acids to culture media did not inhibit the normal growth of the shigellas. The degree of inhibition was measured by disc assay and showed that the inhibitory substance(s) can be extracellular and diffusible, varying the degrees of inhibition depending on the media tested. When broth was inoculated with mixed cultures of Lactobacillus and Shigella strains, the inhibition began at 6 h and the death phase at 9 h. The higher inhibition was produced by the mixture of lactobacilli (35.5 +/- 2.5% at 6 h culture, 57.4 +/- 1.9% at 9 h and 91.2 +/- 1.2% at 14 h). The degree of inhibition was higher when the relationship pathogen : lactobacilli was 1:10(3). The specific growth rate of lactobacilli and shigella was different in pure or mixed cultures. When the lactobacillus alone was grown for 12 h and the shigellas then added, the numbers of shigellas began to decrease immediately at 37 degrees C. This work shows that the Lactobacillus strains employed in fermented milk can be used to inhibit the growth of Sh. sonnei.     

Studies on the mechanism of haloacetonitrile-induced gastrointestinal toxicity: interaction of dibromoacetonitrile with glutathione and glutathione-S-transferase in rats

The haloacetonitrile, dibromoacetonitrile (DBAN), is a direct-acting genotoxic agent that has been detected in drinking water. In a time course study, male Sprague-Dawley rats were treated with DBAN (75 mg/kg PO), and killed at 0.5, 1, 2, and 4 hr after treatment. In a dose response study, animals were treated orally with various doses of DBAN (25, 50, 75, and 100 mg/kg) and killed at one-half hour after treatment. Control animals received 1 ml/kg PO of the vehicle dimethyl sulfoxide (DMSO). In both experiments blood and organs were collected and stored at -80 degrees C until the time of analysis. At 0.5 hr after treatment, a single oral dose of DBAN caused a significant decrease of glutathione (GSH) concentrations in liver (54% of control) and stomach (6% of control). Hepatic GSH depletion was maximal at 0.5 hr and rebound to the control levels by 4 hr. In contrast, gastric GSH concentrations remained low at all time points. DBAN caused an insignificant change in both kidney and blood GSH levels. DBAN significantly inhibited glutathione-S-transferase (GST) activity in liver and stomach. Hepatic GST inhibition was maximal (34% of control) at 2 hr and minimal (80% of control) at 4 hr. Meanwhile, in the stomach GST activity was inhibited at 1 hr (60% of control) and remained low at all times after treatment. Both GSH depletion and GST inhibition were dose-dependent. This study indicates that GSH and GST play an important role in the metabolism and detoxification of DBAN in rats. The prolonged depletion of GSH and inhibition of GST in the gastrointestinal (GI) tissues suggest that the GI tract is a major target for DBAN toxicity.     

Purification and substrate specificity of heparitinase I and heparitinase II from Flavobacterium heparinum. Analyses of the heparin and heparan sulfate degradation products by 13C NMR spectroscopy

The purification of two heparitinases and a heparinase, in high yields from Flavobacterium heparinum was achieved by a combination of molecular sieving and cation-exchange chromatography. Heparinase acts upon N-sulfated glucosaminido-L-iduronic acid linkages of heparin. Substitution of N-sulfate by N-acetyl groups renders the heparin molecule resistant to degradation by the enzyme. Heparitinase I acts on N-acetylated or N-sulfated glucosaminido-glucuronic acid linkages of the heparan sulfate. Sulfate groups at the 6-position of the glucosamine moiety of the heparan sulfate chains seem to be impeditive for heparitinase I action. Heparitinase II acts upon heparan sulfate producing disulfated, N-sulfated and N-acetylated-6-sulfated disaccharides, and small amounts of N-acetylated disaccharide. These and other results suggest that heparitinase II acts preferentially upon N,6-sulfated glucosaminido-glucuronic acid linkages. The total degradation of heparan sulfate is only achieved by the combined action of both heparitinases. The 13C NMR spectra of the disaccharides formed from heparan sulfate and a heparin oligosaccharide formed by the action of the heparitinases are in accordance to the proposed mode of action of the enzymes. Comparative studies of the enzymes with the commercially available heparinase and heparitinase are described.